Determine if the file that is being uploaded contains plain text

Added functionality to determine if the file being uploaded contains plain text. This should resolve the issue where all non-text files were being base64 encoded even if they contain plain text.

app/assets/javascripts/ide/components/new_dropdown/upload.vue

@@ -25,14 +25,14 @@ export default {
     },
   },
   methods: {
-    createFile(target, file, isText) {
+    createFile(target, file) {
       const { name } = file;
       let { result } = target;
-      if (!isText) {
-        // eslint-disable-next-line prefer-destructuring
-        result = result.split('base64,')[1];
-      }
+      let encodedContent = result.split('base64,')[1];
+      let rawContent = atob(encodedContent);
+      let isText = rawContent.match(/[^\u0000-\u007f]/) ? false : true; // u0000-u007f is the non-ascii character range
+      result = isText ? rawContent : encodedContent;
       this.$emit('create', {
         name: `${this.path ? `${this.path}/` : ''}${name}`,
@@ -43,15 +43,9 @@ export default {
     },
     readFile(file) {
       const reader = new FileReader();
-      const isText = file.type.match(/text.*/) !== null;
-      reader.addEventListener('load', e => this.createFile(e.target, file, isText), { once: true });
-
-      if (isText) {
-        reader.readAsText(file);
-      } else {
-        reader.readAsDataURL(file);
-      }
+      reader.addEventListener('load', e => this.createFile(e.target, file), { once: true });
+      reader.readAsDataURL(file);
     },
     openFile() {
       Array.from(this.$refs.fileUpload.files).forEach(file => this.readFile(file));